Lower GI histology Flashcards
hirschprungs disease
absence of ganglion cells in the myenteric plexus- distal colon fails to dilate, 80% male, constipation, abdominal distension, vomiting, overflow diarrhoea, associated with downs syndrome
what does a biopsy show in hiirschprungs disease
hypertrophied nerve fibres but not ganglia
what is a volvulus
complete twisting of a loop of bowel at mesenteric base around vascular pedical, occurs in small bowel in inhants and sigmoid colon in elderly
diverticular disease
low fiber diet, weak points in wall of bowel, 90% in left colon, barium enema, endoscopy , complications, diverticulitis, gross perforation, fistula
Acute colitis causes
infection, drug, toxins, chemo, radiation
chronic colitis
crohns, UC, TB
Effects of infection
secretory dirrhoea (toxin), exudative diarrhoea (invasion and mucosal damage)< severe tissue damage, peforatin, systemic illness
pseudomebranous colitis
antibiotic associated colitis with pseudomembrane formation caused by c diff exotoxins
diagnosis of pseudomembranous colitis
gross histology cornflake appearance, cdiff toxin stool assay, metronidazole
microscope appearance of pseudomembranous colitis
Mucopurulent exudate erupts out of crypts to form a mushroom-like cloud with a linear configuration of karyorrhectic debris and neutrophils that adheres to surface
Superficial crypts show patchy necrosis and dilation
Later in disease, entire crypt becomes necrotic and disease resembles ischemic colitis
Adjacent mucosa is normal, but may be covered by pseudomembrane
Superficial lamina propria contains dense neutrophils and some capillary fibrin thromb
where does infarction occur in the gut
watershed zones e.g. splenic flexure (SMA and IMA), and rectosigmoid (IMA and internal iliac)
ischaemic colitis aetiology
arterial occlusion, venous occlusion, small vessal disease, low flow states, obstruction
crohns disease epidemiology
peak onset, teens twenties, western populations, white, jewish, smoking
crohns disease presentation
whole GI tract can be affected, mouth to anus, skip lesions, transmural inflammation, non caseating granulomas, sinus fistula formation
crohns disease histology
fat wrapping, thick rubber hose like wall, narrow lumen, cobblestone mucosa, linear ulcers, fissures, anbscesses
